Method and apparatus for ensuring reception of conditional access information in multi-tuner receivers

ABSTRACT

A method and apparatus for receiving conditional access information (CAI) on one or more of a plurality of tuners while the user is selecting different channels is disclosed. The method comprises the steps of receiving the CAI on a first tuner tuned to a first channel; identifying the first tuner as the tuner receiving the CAI; and commanding the second tuner to receive the CAI after receiving a command to retune the first tuner from the first channel to a second channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is related to the following patent application,which is hereby incorporated by reference herein:

[0002] U.S. patent application Ser. No. ______, entitled “METHOD ANDAPPARATUS FOR MINIMIZING CONDITIONAL ACCESS INFORMATION OVERHEAD WHILEENSURING CONDITIONAL ACCESS INFORMATION RECEPTION IN MULTI-TUNERRECEIVERS,” by Peter M. Klauss, Raynold M. Kahn, Gregory J. Gagnon, andDavid D. Ha, attorney's docket number PD-200184, filed on same dateherewith.

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to systems and methods forproviding video program material to subscribers, and in particular to amethod and system for ensuring reception of conditional accessinformation in multi-tuner receivers.

[0005] 2. Description of the Related Art

[0006] Media programs such as video and audio information can bedistributed to households via a variety of methods including terrestrialtransmitters, cable, the Internet, and satellites. Each of these mediadistribution systems implement a large number of channels, and aretherefore capable of providing a large number of concurrently broadcastmedia programs to each household.

[0007] While existing systems provide a large number of channels, thereis a trend towards even greater numbers of channels and greaterbandwidth requirements on existing channels to accommodate, for example,HDTV. With regard to satellite-based media program distribution systems,the increased channels and bandwidth demands can be satisfied by theintroduction of additional satellites and/or the use of additionaltransponders on the satellites.

[0008] In order to receive signals from each of the plurality ofsatellites, ground stations can include multiple antennae (each directedto a satellite of interest) coupled to a single tuner, multiplereceiving elements (referred to as low noise block converters, or LNBs)using a single reflector, or multiple antennae and multiple tuners.

[0009] At the same time, it is important that the media programstransmitted by the satellites be protected from unauthorized receptionand/or reproduction. This is accomplished by encrypting the mediaprograms, and broadcasting data that (along with hardware disposed atthe receiver station) is used to decrypt the media programs.

[0010] Unfortunately, when consumers go from one channel to another, thechannel selection may require the receiver to switch from one tuner tothe other (since the second channel is being transmitted by a differentsatellite than the first channel). In some cases, this switching fromone tuner to the other can temporarily interrupt the reception of theinformation required to decrypt the desired media information. Thisproblem is especially notable when the user is rapidly changingchannels, or “channel surfing.”

[0011] What is needed is a system and method for assuring that theinformation required to decrypt media programs is readily available,even in circumstances when a channel command requires switching tunersfrom one to another. The present invention satisfies that need.

SUMMARY OF THE INVENTION

[0012] In summary, the present invention describes a system and methodfor receiving conditional access information (CAI) on one or more of aplurality of tuners while the user is selecting different channels. Themethod comprises the steps of receiving the CAI on a first tuner tunedto a first channel; identifying the first tuner as the tuner receivingthe CAI; and commanding the second tuner to receive the CAI afterreceiving a command to retune the first tuner from the first channel toa second channel. In one embodiment, the apparatus comprises a receiverfor receiving a media program and conditional access information (CAI)for decrypting the media program. The receiver comprises a first tunertunable to a first channel to receive the CAI; a second tuner tunable tothe first channel and the second channel; and a verifier,communicatively coupled to the first tuner and the second tuner, theverifier for decrypting the media program using the conditional accessinformation (CAI), for identifying the first tuner as the tunerreceiving the CAI, and for commanding the second tuner to receive theCAI after the receiver is commanded to retune the first tuner from thefirst channel to a second channel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Referring now to the drawings in which like reference numbersrepresent corresponding parts throughout:

[0014]FIG. 1 is a diagram showing an overview of a video distributionsystem;

[0015]FIG. 2 is a block diagram showing a typical uplink configurationshowing how video program material is uplinked to a satellite fortransmission to subscribers using a single transponder;

[0016]FIG. 3A is a diagram of a representative data stream received froma satellite;

[0017]FIG. 3B is a diagram illustrating the structure of a data packet;

[0018]FIG. 4 is a block diagram illustrating a high-level block diagramof the IRD; and

[0019] FIGS. 5A-5C are flow charts presenting illustrative process stepsthat can be used to practice one embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] In the following description, reference is made to theaccompanying drawings which form a part hereof, and which show, by wayof illustration, several embodiments of the present invention. It isunderstood that other embodiments may be utilized and structural changesmay be made without departing from the scope of the present invention.

Video Distribution System

[0021]FIG. 1 is a diagram illustrating an overview of a videodistribution system 100. The video distribution system 100 comprises acontrol center 102 in communication with an uplink center 104 via aground link 114 and an integrated receiver/decoder (IRD) 132 at receiverstation 130 via a public switched telephone network (PSTN) or other link120. The control center 102 provides program material to the uplinkcenter 104, coordinates with the receiver station 130 to offersubscribers 110 pay-per-view (PPV) program services, including billingand associated decryption of video programs.

[0022] The uplink center 104 receives program material and programcontrol information from the control center 102, and using an uplinkantenna 106, transmits the program material and program controlinformation to the satellite 108. The satellite 108 receives andprocesses this information, and transmits the video programs and controlinformation to the subscriber 110 at the receiver station 130 viadownlink 118. The subscriber 110 receives this information using thesubscriber antenna 112 communicatively coupled to the IRD 132.

[0023] The video distribution system 100 can comprise a plurality ofsatellites 108 in order to provide wider terrestrial coverage, toprovide additional channels, or to provide additional bandwidth perchannel. In one embodiment of the invention, each satellite comprises 16transponders to receive and transmit program material and other controldata from the uplink center 104 and provide it to the subscribers 110.However, using data compression and multiplexing techniques the channelcapabilities are far greater. For example, two satellites 108 workingtogether can receive and broadcast over 150 conventional (non-HDTV)audio and video channels via 32 transponders.

[0024] While the invention disclosed herein will be described withreference to a satellite based video distribution system 100, thepresent invention may also be practiced with terrestrial-basedtransmission of program information, whether by traditional broadcastingmeans, cable, or other means. Further, the different functionscollectively allocated among the control center 102 and the uplinkcenter 104 as described above can be reallocated as desired withoutdeparting from the intended scope of the present invention.

[0025] Although the foregoing has been described with respect to anembodiment in which the program material delivered to the subscriber isvideo (and audio) program material such as a movie, the foregoing methodcan be used to deliver program material comprising purely audioinformation or data as well.

[0026]FIG. 2 is a block diagram showing a typical uplink configurationfor a single satellite 108 transponder, showing how video programmaterial is uplinked to the satellite 108 by the control center 102 andthe uplink center 104. FIG. 2 shows three video channels (which could beaugmented respectively with one or more audio channels for high fidelitymusic, soundtrack information, or a secondary audio program fortransmitting foreign languages), and a data channel from a computer datasource 206.

[0027] The video channels are provided by a program source of videomaterial 200A-200C (collectively referred to hereinafter as videosource(s) 200). The data from each video program source 200 is providedto an encoder 202A-202C (collectively referred to hereinafter asencoder(s) 202). Each of the encoders accepts a program time stamp (PTS)from the controller 216. The PTS is a wrap-around binary time stamp thatis used to assure that the video information is properly synchronizedwith the audio information after encoding and decoding. A PTS time stampis sent with each I-frame of the MPEG encoded data.

[0028] In one embodiment of the present invention, each encoder 202 is asecond generation Motion Picture Experts Group (MPEG-2) encoder, butother decoders implementing other coding techniques can be used as well.The data channel can be subjected to a similar compression scheme by anencoder (not shown), but such compression is usually either unnecessary,or performed by computer programs in the computer data source (forexample, photographic data is typically compressed into *.TIF files or*.JPG files before transmission). After encoding by the encoders 202,the signals are converted into data packets by a packetizer 204A-204F(collectively referred to hereinafter as packetizer(s) 204) associatedwith each source 200.

[0029] The data packets are assembled using a reference from the systemclock 214 (SCR), a control word (CW) generated by the conditional accessmanager 208, and a system channel identifier (SCID) that associates eachof the data packets that are broadcast to the subscriber with a programchannel. This information is transmitted to the packetizers 204 for usein generating the data packets. These data packets are then multiplexedinto serial data, encoded, modulated, and transmitted. A special packetknown as a control word packet (CWP) which comprises control dataincluding the control word (CW) and other control data used in supportof providing conditional access to the program material is alsoencrypted and transmitted.

[0030]FIG. 3A is a diagram of a representative data stream. The firstpacket segment 302 comprises information from video channel 1 (datacoming from, for example, the first video program source 200A). The nextpacket segment 304 comprises computer data information that wasobtained, for example from the computer data source 206. The next packetsegment 306 comprises information from video channel 5 (from one of thevideo program sources 200), and the next packet segment includesinformation from video channel 1 (again, coming from the first videoprogram source 200A). The data stream therefore comprises a series ofpackets from any one of the data sources in an order determined by thecontroller 216. The data stream is encrypted by the encryption module218, modulated by the modulator 220 (typically using a QPSK modulationscheme), and provided to the transmitter 222, which broadcasts themodulated data stream on a frequency bandwidth to the satellite via theantenna 106.

[0031] Subscribers 110 receive media programs via a subscriber receiveror IRD 132. Using the SCID, the IRD 132 reassembles the packets toregenerate the program material for each of the channels. As shown inFIG. 3A, null packets created by the null packet module 312 may beinserted into the data stream as desired.

[0032]FIG. 3B is a diagram of a data packet. Each data packet (e.g.302-316) is 147 bytes long, and comprises a number of packet segments.The first packet segment 320 comprises two bytes of informationcontaining the SCID and flags. The SCID is a unique 12-bit number thatuniquely identifies the data packet's data channel. The flags include 4bits that are used to control whether the packet is encrypted, and whatkey must be used to decrypt the packet. The second packet segment 322 ismade up of a 4-bit packet type indicator and a 4-bit continuity counter.The packet type identifies the packet as one of the four data types(video, audio, data, or null). When combined with the SCID, the packettype determines how the data packet will be used. The continuity counterincrements once for each packet type and SCID. The next packet segment324 comprises 127 bytes of payload data, which is a portion of the videoprogram provided by the video program source 200. The final packetsegment 326 is data required to perform forward error correction.

Encryption of Media Programs

[0033] Media programs are encrypted by the encryption module 218 beforetransmission to assure that they are received and viewed only byauthorized subscribers. Each media program is encrypted according to anconditional access information (CAI). In one embodiment, the conditionalaccess information includes an alphanumeric encryption key referred tohereinafter as a control word (CW). This encryption can be accomplishedby a variety of data encryption techniques, including the dataencryption standard (DES) and the Rivest-Shamir-Adleman (RSA) algorithm.

[0034] To decrypt the media programs, the subscriber's 110 IRD 132 mustalso have access to the CW. To maintain security, CWs are nottransmitted to the IRD 132 plaintext. Instead, CWs are encrypted beforetransmission to the subscriber's IRD 132. The encrypted CW istransmitted to the subscriber's IRD 132 in a control word (data) packet.

[0035] In one embodiment, the data in the control word packet (CWP)(which is also hereinafter alternatively referred to as a conditionalaccess packet (CAP)), including the CW, is encrypted and decrypted viawhat is referred to hereinafter as an input/output (I/O) indecipherablealgorithm.

[0036] An I/O indecipherable algorithm is an algorithm that is appliedto an input data stream to produce an output data stream. Although theinput data stream uniquely determines the output data stream, thealgorithm selected is such that it's characteristics cannot bedeciphered from a comparison of even a large number of input and outputdata streams. The security of this algorithm can be further increased byadding additional functional elements which are non-stationary (that is,they change as a function of time). When such an algorithm is providedwith identical input streams, the output stream provided at a givenpoint in time may be different than the output stream provided atanother time.

[0037] So long as the encryption module 218 and the IRD 132 share thesame I/O indecipherable algorithm, the IRD 132 can decode theinformation in the CWP to retrieve the CW. Then, using the CW, the IRD132 can decrypt the media program so that it can be presented to thesubscriber 110.

[0038] To further discourage piracy, the control data needed to decryptand assemble data packets into viewable media programs may betime-varying (the validity of the control data in a CWP to decode aparticular media program changes with time). This can be implemented ina variety of ways.

[0039] For example, since each CWP is associated with a SCID for eachmedia program, the SCID related to each CWP could change over time.

[0040] Another way to implement time-varying control data is toassociate time stamps with the received data stream and the CWP controldata. In this case, successful decoding of the CWP to produce the CWwould require the proper relationship between the time stamps for thedata stream and the control data in the CWP. This relationship can bedefined, for example, by changing the decryption scheme used to generatethe CW from the CWP according to the received time stamp for the datastream. In this case, if the time stamp of the received data stream doesnot match the expected value, the wrong decryption scheme will beselected and the proper CW (to decrypt the program material) will not beproduced. If, however, the time stamp of the received data streammatches the expected value, the proper decryption scheme will beselected, and the CWP decryption scheme will yield the proper CW.

Subscriber Reception and Decryption of Media Programs

[0041]FIG. 4 is a simplified block diagram of an IRD 132. The IRD 132receives and decrypts the media programs broadcast by the videodistribution system 100. These media programs are streamed to the IRD132 in real time, and may include, for example, video, audio, or dataservices.

[0042] The media programs may be transmitted by a plurality ofsatellites such as satellite 108A and 108B (hereinafter alternativelycollectively referred to as satellite(s) 108, each of which typicallyincludes a plurality of transponders 450-456.

[0043] The IRD 132 is communicatively coupleable to a conditional accessmodule (CAM) 406. The CAM 406 is typically implemented in a smart cardor similar device, which is provided to the subscriber 110 to beinserted into the IRD 132. The CAM 406 interfaces with a conditionalaccess verifier (CAV) 408 which performs at least some of the functionsnecessary to verify that the subscriber 110 is entitled to access themedia programs. The CAV is communicatively coupled to the tuner(s) 410via other elements in the IRD 132, including the microcontroller andmemory 414.

[0044] In the illustrated embodiment, the CAV 414 is alsocommunicatively coupled to the tuners 410. This permits the CAV toreceive information from the tuners regarding whichsatellite/transponder/channel each tuner is tuned to and to supplycommands to the tuners 410 to switch channels at appropriate times. Inanother embodiment, the CAV 414 is not directly coupled to the tuners,but receives information regarding the tuners 410 via the microprocessorand memory 414 (which controls the tuners and receives information fromthem) and provides commands to the tuners via the microprocessor andmemory 414 as well.

[0045] The CAV 408 may be communicatively coupled to the CAM 406 via ametadata analysis module (MAM) 411. Using the information such as thatwhich can be stored in a metadata table, the MAM 411 acts as agate-keeper to determine whether stored media programs will be decryptedand presented to the subscriber 110. This is accomplished by comparingthe metadata values with measured or accumulated values. The CAV 408 andthe MAM 411 can be implemented as separate modules from thetransport/demux/decryptor 412 and the microcontroller and memory 414 asshown, or may be implemented via software instructions stored in thememory and performed by the microcontroller 414.

[0046] In one embodiment, the IRD 132 comprises a plurality of tunerssuch as first tuner 410A and second tuner 410B and nth tuner 410N(alternatively referred to hereinafter as tuner(s) 410), a transport anddemultiplexing module (TDM) 412, which operates under control of amicrocontroller and associated memory 414, a source decoder 416 andcommunicatively coupled random access memory (RAM) 418, and a user I/Odevice for accepting subscriber 110 commands and for providing outputinformation to the subscriber.

[0047] Each of the tuners 410 receive the data packets from the videodistribution system and provides the packets to the TDM 412. The use ofmultiple tuners 410 allows the IRD 132 to quickly tune a signal from oneof a plurality of satellites without moving the antenna or the antennareflector. The use of two tuners also allows the IRD 132 to receivemedia program information at a higher bandwidth by receiving informationwith both tuners simultaneously. This can be implemented by dedicatingeach tuner to a different low noise block converter (LNB) or an entirelydifferent antenna than the other tuner 410.

[0048] Using the SCIDs associated with each media program, the TDM 412reassembles the data packets according to the channel selected by thesubscriber 110, and unencrypts the media programs using the CW key. TheTDM 412 can be implemented by a single secure chip, and iscommunicatively coupled to a microcontroller and memory 414.

[0049] Once the media programs are unencrypted, they are provided to thesource decoder 416 which decodes the media program data according toMPEG or JPEG standards as appropriate. The decoded media program is thenprovided to a D/A converter (if necessary) and provided to externalinterfaces 404 which can include a media program presentation devicesuch as a television, an audio system, or a computer. The source decoder416 makes use of communicatively coupled RAM 418 to perform thesefunctions.

[0050] The CW key is obtained from the CWP using the CAV 408 and the CAM406. The TDM 412 provides the CWP to the CAM 406 via the CAV 408. TheCAM 406 uses the I/O indecipherable algorithm to generate the CW, whichis provided back to the TDM 412. The TDM 412 uses the CW to decrypt themedia programs. In most IRDs 132, the CAV 408 and the CAM 406 arecapable of decrypting one video/audio/data media program at a time.

[0051] As described above, to discourage potential pirates, the controldata in the CWP used to decode a particular media program may changewith time so that it only produces the proper CW when applied to a mediaprogram having the proper time stamp. In this case, the CAM 406 canselect and/or control the decryption scheme (e.g. the I/O indecipherablealgorithm) according to the time stamp associated with the data streamcarrying the media program. If the media program is sufficientlydisassociated in time, the improper decryption scheme will be used, andthe proper CW to decode the media program will not be produced.

[0052] Further details regarding the encryption and decryption of mediaprograms can be found in co-pending and commonly assigned U.S. patentapplication Ser. No. 09/491,959, which application is herebyincorporated by reference herein.

[0053]FIG. 5A is a flow chart presenting illustrative process steps thatcan be used to practice one embodiment of the present invention.Conditional access information (CAI) is received on a first tuner 410Atuned to a first channel, as shown in block 502. This CAI is used, forexample, to decrypt the media program currently being viewed the user. Acommand is received to change the channel being viewed by the user, asshown in block 504. The receiver 132 identifies which of the tuners(e.g. 410A, 410B . . . 410N) is receiving the CAI, as shown in block506. This can occur after the receipt of the channel change command (asillustrated in FIG. 5A), after the channel change command, or may bedetermined periodically or on an ongoing basis. A determination is madeas to whether the channel change command would require retuning thefirst tuner (the tuner currently receiving the CAI) away from thecurrent channel (e.g. to another channel), as shown in block 508. Ifthis is the case, there is the possibility that the receipt of the CAIinformation will be temporarily interrupted, compromising the user'sability to surf rapidly from one channel to another.

[0054] A command is provided to a different tuner (e.g. second tuner410B or 410N) to tune to a channel (and a satellite/transpondercombination) to receive the CAI information required to decrypt themedia program provided on the selected channel. This is shown in block510. The first tuner is the retuned from the first channel to the secondchannel, as was implicated in the channel command. Since the secondtuner is now receiving the CAI, the change in channels can be performedwithout a temporary interruption in the decryption of the media program,as shown in block 514.

[0055] In one embodiment, the first tuner is not retuned from the firstchannel to the second channel until it is confirmed that the secondtuner is receiving the CAI. This is shown in block 512. This effectivelyprevents any channel change to be performed until an appropriate CAI isreceived.

[0056]FIG. 5B is flow chart illustrating exemplary process steps thatcan be used to practice another embodiment of the invention. In thisembodiment, the tuning step shown in block 510 includes a determinationas to which of the plurality of tuners 410 should be selected to receivethe CAI. Of the available tuners, this technique chooses the tuner thatis retuned least often, as shown in block 518. Since this tuner ishistorically retuned less often than the others, using this tuner toreceive the CAI should result in fewer service disruptions (e.g. thedecision shown in block 508 will result in a “no” more often than if theother tuners were utilized).

[0057]FIG. 5C is a flow chart illustrating another embodiment of thepresent invention. In this embodiment, in performing the operation ofblock 510, each of the tuners 410A-410N are selected in order in around-robin fashion (e.g. 410A, 410B, 410N, 410A, 410B, 410N . . . ).This is shown in block 520. Since this only occurs when block 508determines that the commanded channel change requires that the tunerreceiving the CAI information change from one channel to another, theround robin selection of the next succeeding tuner will assure that thetuners that are more typically tuned to the CAI channels remain so. Inother words, if a particular channel is dedicated to receiving the CAIinformation, the round robin technique will eventually select thatchannel, and no further retuning will be required. Further in caseswhere a particular tuner is not dedicated to receive CAI information,but infrequently receives anything else, the round robin technique willeventually select that channel for receiving the CAI information, andthe tuner will remain tuned to that channel until such time (which isinfrequent) as the tuner is required to tune to another. Therefore,using the round robin technique, the channels which are statisticallymore likely to not require retuning are tuned to statistically moreoften.

[0058] The foregoing method steps can be implemented in a number ofways, including by use of software modules and hardware modules having aplurality interconnected circuit elements. In one embodiment of thepresent invention, the steps shown in FIGS. 5A-5C are performed at leastin part in the CAV 408, by a hardware module and/or a software module.The processor for performing the operations defined in the softwaremodule may be stored in a CAV 408 dedicated memory coupled to a CAV 408dedicated processor, or may be performed by the microcontroller andassociated memory 414. Other elements, such as the CAM 406 and/or themicrocontroller and memory 414 may perform some or all of the functionsdescribed in FIGS. 5A-5C.

Conclusion

[0059] The foregoing description of the preferred embodiment of theinvention has been presented for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. Many modifications andvariations are possible in light of the above teaching. For example, theencryption functions described herein could be performed by separateencryption/decryption modules, or a single multi-purposeencryption/decryption module can be utilized to perform theencryption/decryption functions of many separate modules.

[0060] It is intended that the scope of the invention be limited not bythis detailed description, but rather by the claims appended hereto. Theabove specification, examples and data provide a complete description ofthe manufacture and use of the composition of the invention. Since manyembodiments of the invention can be made without departing from thespirit and scope of the invention, the invention resides in the claimshereinafter appended.

What is claimed is:
 1. A method of receiving conditional accessinformation (CAI) on one or more of a plurality of tuners comprising afirst tuner and a second tuner, the CAI usable to decrypt one or moremedia programs, the method comprising the steps of: receiving the CAI ona first tuner tuned to a first channel; identifying the first tuner asthe tuner receiving the CAI; and commanding the second tuner to receivethe CAI.
 2. The method of claim 1, wherein the step of commanding thesecond tuner to receive the CAI is performed before retuning the firsttuner from the first channel to the second channel.
 3. The method ofclaim 1, further comprising the steps of: confirming that the secondtuner is receiving the CAI; and commanding the first tuner to retune thefirst tuner from the first channel to the second channel.
 4. The methodof claim 3, wherein the step of commanding the second tuner to receivethe CAI further comprises the steps of: determining which of theplurality of tuners is retuned least frequently among the plurality oftuner; and designating the tuner that is retuned least frequently amongthe plurality of tuners as the second tuner.
 5. The method of claim 1,wherein each of the plurality of tuners is identifiable in a round robinsequence and the step of commanding the second tuner to receive the CAIfurther comprises the steps of: designating a tuner that follows thefirst tuner in the round robin sequence as the second tuner.
 6. Anapparatus for receiving conditional access information (CAI) on one ormore of a plurality of tuners comprising a first tuner and a secondtuner, the CAI usable to decrypt one or more media programs, the methodcomprising: means for receiving the CAI on a first tuner tuned to afirst channel; means for identifying the first tuner as the tunerreceiving the CAI; and means for commanding the second tuner to receivethe CAI.
 7. The apparatus of claim 6, wherein the means for commandingthe second tuner to receive the CAI is performed before retuning thefirst tuner from the first channel to the second channel.
 8. Theapparatus of claim 6, further comprising: means for confirming that thesecond tuner is receiving the CAI; and means for commanding the firsttuner to retune the first tuner from the first channel to the secondchannel.
 9. The apparatus of claim 8, wherein the step of commanding thesecond tuner to receive the CAI further comprises the steps of:determining which of the plurality of tuners is retuned least frequentlyamong the plurality of tuner; and designating the tuner that is retunedleast frequently among the plurality of tuners as the second tuner. 10.The apparatus of claim 6, wherein each of the plurality of tuners isidentifiable in a round robin sequence and the step of commanding thesecond tuner to receive the CAI further comprises the steps of:designating a tuner that follows the first tuner in the round robinsequence as the second tuner.
 11. A receiver for receiving a mediaprogram and conditional access information (CAI) for decrypting themedia program, comprising: a first tuner tunable to a first channel toreceive the CAI a second tuner tunable to the first channel and thesecond channel; and a verifier, communicatively coupled to the firsttuner and the second tuner, the verifier for decrypting the mediaprogram using the conditional access information (CAI), for identifyingthe first tuner as the tuner receiving the CAI, and for commanding thesecond tuner to receive the CAI.
 12. The receiver of claim 11, whereinthe verifier commands the second tuner to receive the CAI before thefirst tuner is retuned from the first channel to the second channel. 13.The receiver of claim 11, wherein the verifier further comprises amodule for confirming that the second tuner is receiving the CAI beforethe first tuner is retuned from the first channel to the second channel.14. The receiver of claim 13, wherein the verifier further comprises: asecond module for determining which of the plurality of tuners isretuned least frequently among the plurality of tuner; a third modulefor designating the tuner that is retuned least frequently among theplurality of tuners as the second tuner.
 15. The receiver of claim 11,wherein each of the plurality of tuners is identifiable in a round robinsequence and the verifier further comprises: a fourth module fordesignating a tuner that follows the first tuner in the round robinsequence as the second tuner.
 16. A program storage device, readable bya computer, tangibly embodying at least one program of instructionsexecutable by the computer to perform method steps of receivingconditional access information (CAI) on one or more of a plurality oftuners comprising a first tuner and a second tuner, the CAI usable todecrypt one or more media programs, the method steps comprising thesteps of: receiving the CAI on a first tuner tuned to a first channel;identifying the first tuner as the tuner receiving the CAI; andcommanding the second tuner to receive the CAI.
 17. The program storagedevice of claim 16, wherein the method step of commanding the secondtuner to receive the CAI is performed before retuning the first tunerfrom the first channel to the second channel.
 18. The program storagedevice of claim 16, wherein the method steps further comprise the stepsof: confirming that the second tuner is receiving the CAI; andcommanding the first tuner to retune the first tuner from the firstchannel to the second channel.
 19. The program storage device of claim18, wherein the method step of commanding the second tuner to receivethe CAI further comprises the method steps of: determining which of theplurality of tuners is retuned least frequently among the plurality oftuner; and designating the tuner that is retuned least frequently amongthe plurality of tuners as the second tuner.
 20. The program storagedevice of claim 16, wherein each of the plurality of tuners isidentifiable in a round robin sequence and the method step of commandingthe second tuner to receive the CAI further comprises the method stepsof: designating a tuner that follows the first tuner in the round robinsequence as the second tuner.